McGahee disclosed a credit card monitor in his U.S. Pat. No. 3,959,789 which consists of a plurality of switches formed from conductive means affixed to the surface of separators in a card carrying case. The separators are biased together and the electrical contacts affixed thereto are interconnected to form a plurality of normally closed, electrically parallel switches. The switches are interconnected to provide electrical current to a time delay means which is adapted to energize a sensory warning a predetermined time after closure of one of the switches. In its normal operation, credit cards are inserted between all of the separators so that removal of any card will result in the closure of one switch to sense the warning for reminding its owner.
However, if a thief of pickpocket who may steal the complete card carrying case other than an individual card without removing any card from the carrying case and without sensing the alarm so that McGahee's device still can not serve as a satisfactory security means such as for warning a pickpocket behavior. It is therefore to expect a warning device for sensing an alarm when completely removing a wallet, a valuable card or document from an owner's pocket by a thief or pickpocket for ensuring the security of the owner's articles kept in his or her pocket.